Where are they? Are we alone? And when will we know?
By Rupert P Cole, on 7 September 2012
The search for extra-terrestrial life isn’t exactly a success story. But our incessant desire to find some drives us to look. Wednesday night, a bunch of us crammed into Aberdeen’s Waterstones to hear UCL’s space scientist Dr Maggie Aderin-Pocock speak on the current chances of there being life “out there.”
Maggie’s main job in science has been in engineering satellites and telescopes – a talent she cultivated very early in her life. When she was 14 she built her own telescope, which was 150mm in diameter.
Besides The Clangers, she told us, this was her first real contact with space. Her enthusiasm and curiosity is inspiring. Recently awarded an MBE for her work in science communication, one of her outreach schemes takes school children on “Tours of the Universe”.
Luckily for us, then, our guide in our search for alien life had seen the universe, knew the sights, and even the lingo.
“I see myself as a translator, removing the jargon and highlighting the wonder” – she remarked in 2006, regarding her role as a recipient of the Science and Society Fellowship she holds at UCL.
Looking for life in the universe is, I imagine, a pretty arduous task. Since it’s a fairly big area to cover (billions of light-years), and getting bigger all the time, we might reasonably pose the question: where to start?
Quite sensibly, we began in our own solar system, where we know at least one instance of life exists. But where might the others be hiding, if indeed there are others (and they’re hiding).
We can rule those places out with no atmosphere, like the moon and mercury. Such extreme fluctuations in temperature are not very hospitable for the budding organism.
Venus, where women are allegedly from, has a pretty horrendous atmosphere, consisting of 95% carbon dioxide. So it’s certainly not a pleasant place to live.
Perhaps Mars? Earth’s sister planet, only a bit colder. Rock erosion and formation suggest that there may have once been water (a key life ingredient), possibly frozen in the ground.
If life once graced Mars, it would have had to live beneath the surface due to the UV radiation. Our hopes for finding out currently lie with Curiosity – a very lucky probe. Only one third of the mars probes have survived. Curiosity had to endure a tricky landing, involving a parachute, a jet-pack and a crane.
Maggie told us she wishes to “retire on Mars”. Any trip, she explains, will be significantly cheaper if one way. Apparently, she has met quite a few with this courageous retirement plan.
All things considered, Maggie estimates the probability that there was once life on Mars at 10-20%. It’s certainly a start, considering we have only gone several light minutes.
What about the gas giants? Not at all likely in themselves, but maybe their moons. In 2005, the Huygens probe landed on Saturn’s moon Titan, the first landing in the outer solar system. It lasted 90 minutes, providing a picture of a rocky landscape, atmospheric sounds, but no visible colonies.
As we move further from the sun and solar energy, the possibility of life decreases. Though there are plenty more suns – some 200 billion in our galaxy alone.
The search for life in the Milky Way takes on a whole new character. Currently, scientists are on the hunt for exoplanets, ones that orbit sun (or suns), and that potentially harbour life.
Over 800 have been identified. How are they detected? When they travel across their sun, a dip in light can be perceived. This dip can tell us things like the size of the planet and the speed of its orbit.
Ones within a certain scale of similarity to earth are deemed to be in the goldilocks zone, perhaps just the right conditions for life. In 1961 Frank Drake even devised an equation for estimating the probable amount of life in the Milky Way. For most of the parameters, the values we have are little more than utter guesswork.
The Search for Extra-terrestrial Intelligence (SETI) program has been running since the 1960s, which aims to detect intelligent signals. It’s not so farfetched as it sounds. Dame Jocelyn Bell Burnell’s Nobel-winning discovery of pulsars was first dubbed the “Little Green Man”.
The main problem even if we find something, anything, is distance. Our closest star, Proxima Centauri is four light-years away. At the moment, Voyagers are hurtling towards it at 10.5 miles per second. My journey from London to Aberdeen at this speed would have taken less than a minute. But to Proxima, it will take 77,000 years!
Maggie outlines some options for galactic tourism. City spaceships that populate? Synthetic human foetuses planted to “grow” in a ship? Wormholes may even be, she says, our best bet.
The search for aliens will go on. The Hubble has shown us there are galaxies in deep space where we previously thought there was only space. New telescopes the size of football pitches are due in 50 years, which Maggie tells us will be powerful enough to detect life on exoplanets.
The numbers are encouraging, the possibilities enticing. Maggie is “utterly convinced there’s life out there, but don’t think you will be finding it anytime soon.”
Rupert Cole is a History of Science, Technology and Medicine MSc student in UCL Science and Technology Studies.